1. Field of the Invention
The present invention relates to a method of bonding an ion exchange membrane of a fluorinated polymer to a synthetic resin. More particularly, it relates to a method of bonding an ion exchange membrane of a fluorinated polymer to a synthetic resin with a binder in a form of a net, cloth or porous sheet by heat welding methods.
2. Description of the Prior Art
The ion exchange membrane of a fluorinated polymer is not easily bonded to others even the same membrane. It has been known that only when the ion exchange groups are carboxylic acid groups or ester groups, a bonding with a strength to be practically used can be given. If the ion exchange membrane of a fluorinated polymer is easily bonded to the other synthetic resin product, the synthetic resin part can be used for fitting to a desired equipment. The effective area of the ion exchange membrane can be larger or the ion exchange membrane can be easily processed in a fabrication such as a fabrication by bonding the ion exchange membrane in a bag form.
The strength of the bonded part at the bonding is remarkably high when the ion exchange groups are carboxylic acid groups or ester groups, however the strength of the bonded part becomes weak when the laminated ion exchange membrane is used for an electrolysis of an aqueous solution of sodium chloride because the ion exchange groups are converted into sodium salt groups.
The inventors have studied to find a method of bonding firmly the ion exchange membrane of a fluorinated polymer to the other synthetic resin for a long time without substantial adverse effect of kind of the ion exchange groups.